<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>通用2栏布局</title>
    <style>
        body
        {
            margin: 0px;
            color:white;
        }
        *
        {
            margin:0;
            padding:0;
        }
        .main-title
        {
            text-align: center;
            background-color: blue;
            color: white;
            margin-top:0px;
        }
        .content-wrapper
        {
            width: 100%;
            height: 100%;
            background-color:blue;
        }
    </style>
</head>
<body>
    <div class="app">
        <h1 class="main-title">导航栏</h1>
        <div class="content-wrapper">12345678</div>
    </div>
</body>
</html>